This application relates to a variable area diffuser. In particular, this application relates to a variable area, vane-type-diffuser suitable for use in a compressed air system for an air conditioning pack.
Variable area diffusers utilize multiple vanes that are rotated between different angular positions to vary the throat size of the diffuser. Variable area diffusers can be used in conjunction with, for example, superchargers to vary the flow through an air conditioning system of an aircraft at various altitudes.
The variable area diffuser may be subjected to very high stresses, for example, as the compressor is driven at high speed. The diffuser structure must pass a containment test in which the compressor rotor is rotated at very high speeds until the rotor disintegrates. The debris must stay within its housing so that the debris does not create a hazard to surrounding areas, components or personnel.
Another problem with the diffuser operation is that the structure adjacent to the vanes, such as a backing plate and/or shroud, deflects. It is desirable to maintain a clearance of only a few thousandths on either side of the vane throughout the operation of the diffuser. Deflection of the structure surrounding the vanes can create a binding condition compromising the operation of the diffuser.
What is needed is an improved variable area diffuser with improved operation under applied loads and improved containment of debris in the event of rotor failure.